1. Field of the Invention
The present invention relates to flare-tube assemblies and, more particularly, to flare-tube assemblies which maintain a seal when mated with rough castings and under relatively high temperatures.
2. Description of Related Art
Flare-tube assemblies which provide fluid-tight seals are known. One type of flare-tube assembly commonly used in the art has a tube with a forward facing flared end and a fitting or nut slidably retained on the tubing. The flare is conically-shaped having an angle typically of about 45 degrees to the tube axis. The nut has a shoulder facing the flare which also is at a 45 degree angle to the tube axis. The flare end of the tube is inserted into a coupling member which also has an annular lateral shoulder at an angle of about 45 degrees to the tube axis. As the nut is torqued to thread the nut and coupling together, the shoulder of the nut engages generally the entire rear surface of the flare of the tube and presses the flare against the shoulder of the coupling to establish a fluid-tight seal. Care must be taken, however, to avoid over torquing the nut because the shoulder of the nut will shear the flare off the tube.
This type of flare-tube assembly may fail under several conditions. The flare-tube assembly may not properly seal when the coupling is a raw casting. Leakage can occur when the flare is pressed against a rough and porous surface. The flare-tube assembly also may not properly seal under relatively high temperatures. For example, gas tubing connected directly to some sealed burners of a gas stove may fail if the flare-tube assembly connection exceeds a certain temperature. Some sealed burners may reach temperatures of up to and over 500 degrees Fahrenheit. At this temperature leaks may occur because the metal components of the connection relax. Accordingly, there is a need in the art for an improved flare-tube assembly that provides a fluid-tight seal with a rough and porous coupling surface. Additionally, there is a need in the art for an improved flare-tube assembly which remains sealed without leakage when subjected to relatively high temperatures at which conventional flare-tube assemblies may relax and leak.